External support programs to improve rural drinking water service sustainability: A systematic review.

Achieving sufficient, safe, continuously-available drinking water services in rural areas is a challenge, in high- and especially low-and middle-income countries. External support programs (ESPs) - which may include administrative, financial, and technical assistance - have been hypothesized to contribute to sustainable rural water services. While there are many descriptions of ESPs, a standard terminology and typology of ESP activities does not exist and the effect of ESP activities on system sustainability remains inadequately characterized. We conducted a systematic review of ESPs for rural drinking water systems to identify ESP terminology and describe ESP activities. Findings from 218 publications from low-, middle-, and high-income countries were analyzed. ESP terms were used inconsistently between regions and income classifications. There were few studies describing ESP activities related to mechanized piped water systems. Few studies quantitatively assess the effect of ESPs. Those that did found positive associations with functionality, household satisfaction, household participation, and financial stability. This review is the first comprehensive evaluation of the ESP literature and we derive a definition of external support programs and typology of ESP activities from the descriptions of ESPs. A common understanding of ESPs facilitates discussion and knowledge transfer between stakeholders. Consistent terminology creates a foundation for adapting ESPs to water services in community institutions and for mechanized piped water systems.